Method of and apparatus for launching missiles



M y 1964 A. J. GRAM, JR.. ETAL 3,131,597

METHOD OF AND APPARATUS FOR LAUNCHING MISSILES Filed March 27, 1961 4 Sheets-Sheet l HYDROCARBON FEED \L 1 0 HYDROGEN LAUNCH NG PRODUCER- 14 Tue:

200 PSI 1000F 66\' 700PS| -1200F \N\N COMPRESSION I CHAMBER 50- HEATER :1 52 FuEL- :1

IFUEL STEAM 1, BOILERS STEAM 7590PS| ACCUMULATOR 56 1o'ooF HOT CONDENSER V WELL AND MAKE-UP To WASTE INVENTORS WATER Arthur J. Grum,Jr.

y Charles 'S. Smith 5 ATTORNEY y 1954 A. J. GRAM, JR., ETAL 3,131,597

METHOD OF AND APPARATUS FOR LAUNCHING MISSILES Filed March 27, 1961 4 Sheets-Sheet 2 FIG.2

1 I JNVENTORS Arthur J. Gram, Jr. BY Charles S. Smirh' AT T O RNEY May 5, 1964 A. J. GRAM, JR.. ETAL 3,131,597

METHOD OF AND APPARATUS FOR LAUNCHING MISSILES Filed March 27, 1961 4 Sheets-Sheet 5 5 w M V 2 INVENTORS Arthur J. Gram, Jr.

BY Char es 5. SmiTh ATTORNEY y 1964 A. J. GRAM, JR., ETAL 3,131,597

METHOD OF AND APPARATUS FOR LAUNCHING MISSILES 4 Sheets-Sheet 4 Filed March 27, 1961 FIG.9

E k n. W s R 1 m M {P R E L E m A l I B m N m S s E z m N \P W E G C 5 wm HV N m s s E R D. M o C G a N m V ER G L GER W oBA RM M DAC YH U ip T 5 OOOF 0 O 0 0 O O 0 O 0 5 4 3 m m- $3355 $EcoNos- TIME INVENTORS Arthur J. Gram, Jr.

Charles S; Smirh TIORNEY 3,131,597 NETHOD OF AND APPARATUS FGR LAUNCHING MISSILES Arthur J. Gram, J12, Wadsworth, Ohio, and Charles S.

Smith, Wesfield, N.J., assignors to The Bahcoclr & Wilcox Company, New York, N.Y., a corporation of New The present invention relates in general to methods of and apparatus for launching missiles with controlled ac celeration forces at highexit velocities, and more particularly, to methods of and apparatus for this purpose capable of launching large heavy missiles, such as rockets and space vehicles, with an exit velocity from the launching apparatus capable of carrying the missile through all or substantially part of the earths atmosphere.

It has heretofore been proposed to launch space craft from a long vertical launching tube or gun positioned within a mountain top with an exit velocity intended to insure the vehicle coasting through at least part of the dense portion of the earth atmosphere before ignition of the first rocket engine propulsion stage incorporated in the vehicle. The use of a long vertical launching tube in such an elevated location would insure that the vehicle is accurately directed, and substantially reduce the air drag and friction on the vehicle during the dense atmosphere portion of its flight while providing a reinforced lateral support for the launching tube. The proposed propellant was a gaseous fluid, such as steam or'air, stored under a high pressure in a chamber or pressure vessel located adjacent the base of the launching tube and suddenly released to provide a propelling force on the underside of the missile to be discharged which is initially positioned in the lower portion of the tube. To reduce the back pressure on the missile, the portion of the launching tube above the missile is evacuated after the missile is in its launching position and sealed at its upper end with a frangible closure.

Such proposals are considered impractical under the physical limitations of presently available materials, particularly strength and use temperature limits, when the desired exit velocity from the launching tube is to be in excess of about 2500 feet per second and when the rate of acceleration permissible because, for example, of its adverse effect on the instrumentation in the missile, is not more than one hundred times the gravitational acceleration, i.e. 100 g or 3220 feet per second per second. If it is desired to keep the rate of acceleration of the missile in the. launching tube substantially constant, it would be necessary to keep the propulsion force on the base of the missile while in the launching tube substantially constant. To maintain a constant force on the base of the missile, it

. would be necessary to rapidly increase the gas pressure gas beyond which the gas cannot be forced by its own 7 pressure.

This velocity is normally referred to as the sonic or acoustic velocity, i.e. the velocity of sound in that particular gas. The sonic velocity of a gas is a function of the temperature of the gas and increases as the'gas temperature increases. Gases can be made to travel at velocities above the sonic velocity by expansion processes. However, in such cases the gas pressure rapid- United States Patent 3,131,597. Patented May 5, .1964

2 ly reduces. The velocity of sound in low density gases is much higher than its velocity in high density gases.

Our study of the properties of high pressure and high temperature air indicates that with air temperatures within present material limits, the sonic velocities would be too low to use for high missile exit velocities. The sonic velocity for air at 1000 F. is about 1800 fps, at 2000 F. 2300 fps, andat 3000 F. 2800 f.p.s. Accordingly, compressed air within practical storage vessel temperature limits is obviously insuflicient to attain velocities in excess of 2500 f.p.s. Furthermore, our study of the friction of air in a given tube at such sonic velocities of air and with an air pressure at the base of the missile sufficient to maintain the desired acceleration rate indicates that the pressure and temperature requirements at the bottom of the vertical tube would be beyond the use limits of the pressure vessel materials presently available for containing the air.

The velocity limits for the use of steam as a propellant gas are better than for air, but still much below the desired velocities. Steam at 1000 F. has a sonic velocity of 2350 f.p.s.,'at 2000" 1 .2880 f.p.s., and at 3000 F. 3400 fps. However the friction of steam is so great that the required steam pressure and temperature at the bottom of the vertical launching tube to compensate for the high pressure drop would be much above the strength use limits of the materials presently available for the construction of steam-holding pressure vessels.

The frictional resistance of high velocity gas as Well as the sonic velocity of the gas become more favorable for 1 use as the specific volume of the gas increases, i.e. as the density of the gas decreases. We have found that hydrogen, and to a much lesser extent, helium, are light weight gases suitable for use in accordance with our invention. Helium, however, is twice as heavy as hydrogen, has twice the frictional resistance of hydrogen, and does not have a sonic velocity at practicable temperatures high enough to attain the exit velocities from the launching tube possible with hydrogen. On the other hand, hydrogen has a sonic velocity at 1000 F. of 7073 f.p.s., at 2000 F. of 9069 fps, and at 3000 F. over 10,000 f.p.s. Hydrogen can thus be used as the propellant gas at temperatures from 1000 F. to 3000 F. with missile exit velocities of the order of 2500-10,000 fps. and still be below its sonic velocity at the particular temperature employed. Furthermore, because hydrogen is so light in weight, the frictional resistance and pressure drop in the launching tube will be well within practical design limits.

While hydrogen is considered to have the most desirable properties for a high velocity propellant gas, its mode of use. requires special considerations. If, for example, high pressure high temperature hydrogen was stored in a large sphere so that it could be'release'd through a valve or valves into the bottom of a launching tube containing the missile in such a way that the pressure at the base of the missile would remain substaintially constant, it would be necessary tostore the hydrogen gas at a pressure and temperature high enough so that after release of enough hydrogen to project the missile from the tube, the remainingtemperature would be high enough to keep the sonic velocity above the designed missile exit velocity and the pressure high enough to overcome all friction and,

acceleration losses and still maintain the required pressure at the base of the missile. However, the required storage pressures and temperatures of the hydrogen under such conditions would be well above the limits of materials presently available for the construction of high pressure vessels. a

A further study in the use of hydrogen as a propellant gas was made assuming that hydrogen could be stored in a large sphere at a reasonable pressure and tempera-. ture. In order to raise the pressure and temperature of the hydrogen to get a desired exit velocity, e.g. 8000 f.p.s., it was expected that the controlled combustion of hydrogen with oxygen could be used. It was found that it would require the burning of 17.5% of the hydrogen with oxy-. gen to raise the pressure and temperature and the resulting products of combustion would be /a water vapor and /3 hydrogen. This mixture has a sonic velocity far too low to reach 8000 fps. velocity and would also result in gas friction against the tube so high that the required pressures would be above the permissible practical limits.

Relatively pure hydrogen is thus considered the only gas presently available in commercial quantities suitable for use as a high velocity propellant gas in a launching system of the character described. However, in order to use hydrogen stored at reasonable pressures and temperatures, it is necessary to provide some means of rapidly compressing the hydrogen to raise its pressure and temperature to substantially increase its sonic velocity and compensate for the inherent pressure drop in the launching tube. In accordance with our invention, the amount of hydrogen compressed should be sufficient to at least fill the launching tube when the missile reaches. the tube exit, while the supply of hydrogen to the tube is controlled to maintain a predetermined, preferably substantially constant, pressure on the base of the missile throughout its travel in the tube.

The hydrogen compression chamber is desirably of greater diameter than the launching tube to reduce its length for a given volumetric capacity and to minimize the friction losses therein of both the hydrogen and compression fluid, but not so large a cross-sectional area as to create a problem of undue mixing of the hydrogen and compression fluid when there is direct contact therebetween.

In view of the large amount of compression fluid required for the hydrogen compression and the launching operation, it is desirable that a relatively low cost compression medium be employed and that this be supplied to the compression chamber at a very high pressure and to have a velocity therein below its relatively low sonic velocity. In accordance with the invention the hydrogen is stored in a compression chamber at a relatively low pressure and a moderate temperature and a gaseous compression fluid stored in a separate chamber at a much higher pressure and a similar temperature. The two chambers are connected by one or more conduits containing quick-opening valves which are normally closed to keep the two gases apart until the missile is ready to be launched and then rapidly opened to quickly compress the hydrogen to the desired pressure and temperature.

We have found that the most suitable practical fluid to adiabatically compress the hydrogen to the desired condition is high pressure steam. High pressure steam can be relatively cheaply formed by heating water under pressure. The conditions in the compression chamber are such as to insure the hydrogen will be under a very high pressure and temperature at the end of the compression stroke.

It is considered unnecessary to physically separate the propellant hydrogen and the compression fluid steam by means, such as a free piston in the compression chamber, since the amount of mixing of the steam and hydrogen would be small due to the short period of compression and the large density differences of the gases. The high pressure steam compresses the hydrogen to a temperature very much higher than could be attained by storing heated hydrogen in a pressure vessel. In view of the moderate temperature of the hydrogen gas stored in the compression chamber and the attainment of very high temperatures only for a few seconds during the compression and launching periods, the hydrogen containment materials are not overheated. The heat losses from the hot hydrogen are negligible.

To accelerate a mass to a given velocity in the shortest possible distance without exceeding a maximum permissible acceleration, it is necessary to apply such a rate of acceleration to the mass immediately and to maintain it throughout that distance. In accordance with our invention this is done in the launching tube with the hydrogen exerting a constant pressure on themissile. In order to maintain such a constant pressure on the missile, and therefore a constant rate of acceleration of the missile in the tube, it is necessary to control the supply of hydrogent to the launching tube to continually increase the hydrogen pressure at the lower end of the tube throughout the missile travel therein. This increasing pressure is required to drive the missile, overcome the friction loss of the moving column of hydrogen. and to accelerate the ever increasing weight of hydrogen in the tube. The frictional resistance of the missile in the tube will be insignificant compared to that of the column of hydrogen. The maximum hydrogen velocity in the tube is limited by the maximum practical gas pressure at the bottom of the tube when the missile is leaving the tube and the sonic velocity of the hydrogen. To achieve a constant rate of acceleration in the tube, a non-expansion process with controlled acceleration is thus desirably used. The hydrogen has a temperature insuring a sonic velocity at all times during the launching operation above the designed exit velocity of the missile.

In accordance with the invention, the launching cycle will consist, in general, of the following sequence of steps:

(1) Position the missile in the lower part of the launching tube with provisions for minimizing the subsequent leakage of hydrogen past the missile;

(2) Seal the top or" the launching tube and evacuate the tube and compression chamber to the highest degree practical;

(3) Close the discharge valves from the compression chamber;

' (4) Supply steam at a very high pressure and moderate temperature to the steam accumulator until the desired amount of steam is stored;

(5 Fill the compression chamber with hydrogen at the desired pressure and temperature;

(6) The apparatus is now ready for launching the missile and the launching is effected by:

(a) A full opening of the valve means in the conduit or conduits connecting the steam accumulator to the compression chamber to rapidly compress the hydrogen to the desired high pressure and temperature. Before the completion of the compression, beginning a programmed opening of the valve means controlling the supply of compressed hydrogen to the launching tube, unlocking the missile shoe from the launching tube, so that the missile moves upwardly in the tube at a predetermined acceleration and increasing velocity under the pressure of the following body of hydrogen and the pressure thereon of the body of steam in the compression chamber. The small amount of gas remaining in the upper portion of the tube is pushed ahead of the missile and breaks the seal at the upper end of the tube. The missile passes out of the tube at the desired exit velocity and the following column of high temperature hydrogen bursts into flame on contact with the atmosphere.

' (7) After the launching, the steam flow control valves are closed, there being sufiicient steam flow during the valve closing period to purge the compression chamber and launching tube of hydrogen.

The described launching system is characterized by a lower operating cost per missile launching as compared to existing systems in Which the first propulsion stage is a rocket engine incorporated in the missile or the combustion of an explosive charge is used as the propelling medium. The system minimizes the amount of the relatively expensive hydrogen required by utilizing the relatively inexpensive high pressure steam as the hydrogen compression fluid. The utilization of a selectively controlled group of hydrogen flow control valves in conjunction with the steam flow valves reduces the total number of valves required and permits the rate of acceleration of the missile to be maintained at the optimum constant value or varied therefrom for special conditions. All of the materials of construction required are subject only to operating conditions known to be within their physical capacities.

The various features of novelty which characterize our invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which we have illustrated and described a preferred embodiment of our invention.

Of the drawings: FIG. 1 is a schematic illustration of a preferred location of the missile launching apparatus of our invention;

FIG. 2 is a partly diagrammatic elevation partly in sectionof the launching apparatus;

FIG. 3 is an enlarged fragmentary view of a portion of FIG. 2;

, FIG. 4 is a partial section of the diaphragm seal at the upper end of the launching tube;

FIG. 5 is an enlarged view of one of the water spray connections;

'FIG. 6 is a section taken on the line 66 of FIG. 2; H FIG. 7 is a sectional elevation of one of the control valves;

FIG. 8 is a detail of a portion of the valve shown in FIG. 7;

FIG. 9 is a curve sheet of the launching cycle; and

FIG. 10 is a flow sheet of the system.

In thedrawings, we have illustrated an embodiment of our invention designed for launching a 250,000 lb. missile having a mmmum permissible acceleration of 100 gs at an exit velocity of 8000 fps. and utilizing only materials of construction presently available in commercial quantities. As shown in FIG. 1 the launching installation is preferably on a mountain peak 10, having at least one relatively steep side extending to a low elevation to reduce the length of an access tunnel 12 to the enclosed apparlatus. The higher the launch point above sea level, the lower will be the air drag and friction on the missile after launching. Mountain peaks having elevations of 12,000- 14,000 feet are available at a number of accessible loca- The site is drilled to provide a long vertical shaft in which a launching tube or gun 14 is positioned. The tubecan be formed of large diameter steel pipe sections butt-welded to form a continuous straight tube of great height closed at its lower end. Below the bottom of the tube the area is excavated to permit the installation or assembly of a closed ended vertically elongated heavy walled metal cylinder 16. forming a compression or ram chamber of substantially larger diameter than but having a volume .suflicient .to contain enough hydrogen at the initial pressure and temperature conditions to fill the launching tube 14 at the final conditions. The cylinder opening hydrogen control valves 20 whichin turn are connected by conduits 22 to the lower end portion of the launching tube14. The valves 20 are preferably located in an annular chamber 21 to which access is obtained bya tunnel connection to a vertical elevator shaft 24. A conduit 26 is arranged to supply hydrogen gas at a predetermined pressure and temperature to the lower portion of the cylinder 16. An annular ring 28 surrounds the lower portion of the cylinder 16 and has spray nozzles 30 connected thereto for supplying spray water to the interior of the cylinder 16 for condensing steam therein. A similar spray ring 28 is positioned around the tube 14 above the missile level; A condensate drain 32 is connected to the bottom of the cylinder 16 and a similar drain 33 to the tube 14 superjacent the missile initial lmation.

The provisions for storing a supply of high pressure high temperature steam for compressing the hydrogen in the compression chamber 16 consist of a steel spherical accumulator 34 in a large spherical cavity below the elevation of the compression cylinder 16. A steam supply connection 36 opens into the lower part of the sphere and a condensate return line 38 is connected to the bottom thereof. As shown in FIGS. 2 and 6 the walls of the sphere 34 are backed by a layer of concrete 40, which with the surrounding rock or earth 42, reduces the thickness of the metal required vto'withstand the extremely high steam pressures maintained in the sphere 34. The upper portion of the sphere has a multiplicity of conduits 44 connecting the sphere to a circular series of fast-opening steam control valves 46, similar in construction to the valves 20, positioned in an annular chamber 48 opening to the main access tunnel 12.

In general, the required length of launching tube 14 will increase rapidly with any increase in the desired exit velocity or with any decrease in the constant acceleration rate. The diameter of the tube is desirably increased with increases in exit velocity to reduce the gas friction loss. The weight of the projected missile, as well as the acceleration rate, also affects the diameter of the tube. At the higher exit velocity values a smaller tube diameter will usually accommodate the higher acceleration rates. For a missile of the character described having a diameter of 18 feet, the launching tube 14, for example, will be 21 feet in diameter and nearly 10,000 feet in height. The compression cylinder16 will be feet in diameter. and approximately 1300 feet inlength, and the steam accumulator sphere 34 will be approximately 312 feet in diameter.

The supplies of high pressure high temperature steam and of hot hydrogen gas to the steam accumulator and compression chamber respectively, are advantageously generated by apparatus located in an enlarged section of the main access tunnel 12. FIG. 10 schematically illustrates a suitable plant for the conditions stated above. As indicated, the steam plant consists of a plurality of oncethrough steam boilers 50, 52, receiving a supply of hot water from a hot well 54 through pumps 56 and 58 respectively. The boiler 50 is designed, for example, to produce superheated steam at 700 p.s.i. and 1200 F., while the boiler 52 is of the supercritical type and designed to produce steam at 7500 p.s.i. and 1000 F. The superheated steam from the boiler 50 is delivered through a hydrogen heater 66 and conduit 60 to a hydrogen producer 62 of a known cracking type, having a hydrocarbon feed, such as oil or natural gas thereto, with the hydrogen produced at approximately 200 p.s.i. passing to the hydrogen heater 6%, wherein it is heated to a temperature of 1000 F. by steam from the boiler 50, and delivered through the supply pipe 26 to the compression chamber 16 as desired. In preparation for a launch the accumulator 34 is filled with the supercritical pressure steam. The accumulator when fully charged will hold about four times the Weight of steam used per launch, the consumed steam and any condensed in the sphere being replaced for the next launch. The Weight of steam used is approximately 280 times the weight of hydrogen used under the conditions stated.

In FIGS. 7 and 8 is illustrated one form of fast-opening control valve suitable for either the hydrogen control valves 20 or the steam control valves 46. The valve body has a hydrogen inlet and outlet 92 at a 90 spacing. The flow through the valve is controlled by a piston 94 having a plug 96 seating in a hardened seat 97 in the outlet 92, e The lower end of the piston is enlarged and guided in a cylinder 98 formed in the'valve body. An axial passage 100 through the piston is controlled at its lower end by a pilot valve 102 fitting into a chamber 104 in the valve bottom. The movement of the pilot valve in the chamber 104 is controlled by hydraulic fluid from a supply line 106 controlled by a valve 108. A valve controlled waste connection 110 is connected to the line 106. A valve controlled by-pass 112 opens to opposite sides of the piston 94. A ring gasket 114 in the valve body aids in sealing the main valve while a leakage bleed-off connection 116 opens between the valve seat 97 and the gasket 114.

With this construction when it is desired to open a valve 20 or 46, the valve 108 is closed and the waste line 110 opened to release the pressure in chamber 104. This causes the pilot valve 102 to drop, releasing the pressure in the cylinder 98 and creating a pressure difference across the piston 04 which opens the main valve plug 96. The rate at which the main valve opens can be controlled by adjusting the valve in the waste line 110. The main valve is closed by closing the waste line 110 and opening valve 108, causing the pilot valve 102 to move to its upper closing position. The by-pass line 112 is then opened to provide fluid pressure on the lower side of the piston 94 and cause the main valve to close. Conventional automatic valve operating mechanisms can be used to control the valve movements mentioned.

As shown in FIGS. 2 and 3, the missile 70 to be launched is positioned in the lower end portion of the tube 14 by first positioning a circular shoe or sabot 72 having an upper peripheral flange 74 and lower skirt 76 respectively at a level at which it can be releasably locked to the tube 14 by a series of slidable locking devices 78. The shoe is maintained in gas-tight relation with the tube 14 by the skirt 76 slidably contacting the tube wall. The missile 70 is then loweredinto position on the shoe. 72 by a hoist 82 at the upper end of the tube 14. With the missile in position the upper end of the tube is closed by a frangible diaphragm 84 seal welded thereto. A by-pass line 83 controlled by a valve 85 around the missile and shoe and a vent connection 86 at the top of the tube are opened to permit the compression cylinder 16 and tube 14 to be purged of air with steam from the accumulator 34. Following such purge all valves are. closed, the steam condensed by water sprays and the condensate pumped out through the drains. The result is the formation of a substantial vacuum in both the compression chamber and launching tube. The charging of the accumulator with high pressure steam is then completed and concurrently the compression chamber is charged with hot hydrogen gas. As diagrammatically shown in FIG. 9, the sphere 34 may require one day and the chamber 16 several days for complete charging. Upon the completion of these operations, the missile is ready for launching.

To initiate launching of the missile after it has been positioned as described, and the sphere 34 and cylinder 16 charged with high pressure steam and hothydrogen gas respectively, all of the steam discharge valves 46 are fully opened to impose the steam pressure on the body of hydrogen in the cylinder 16. The pressure and temperature of the body of hydrogen gas is rapidly increased to approximately to desired high values and after a predetermined interval, e.g. 6 /2 seconds, the hydrogen discharge valves 20 are successively opened in accordance with a scheduled program to impose an increasing pressure on the bottom of the shoe 72 and supported missile 70. The shoe 72 is then unlocked by withdrawing the locking devices 78 and the missile 70 and shoe 72 move rapidly up the launching tube 14 with a constant pressure imposed on the underside of the shoe. With the sequential opening of the valves 20, the pressure on the body of hydrogen in the bottom of the launching tube is preferably constantly increased to provide a constant rate of acceleration of the missile and hydrogen column in the tube 14. The small amount of gas remaining in the tube is pushed ahead ofthe missile and breaks the seal of the closure 84 at the upper end of the tube.

At the instant the missile leaves the tube, the steam control valves 46 are closed. The steam left in the cylinder 16 expands and escapes through the launching tube 14, purging the tube of all hydrogen. The high temperature hydrogen bursts into flame on exit from the tube. The hydrogen control valves 20 are then closed, trapping purging steam in the cylinder 16. In this condition, air will fill the launching tube as the steam therein is con: densed and as it escapes from the tube. The tube is then ready for reloading for the next missile launching. After loading the shoe and missile, and installing a new seal diaphragm 84 at the top of the tube, the by-pass line valve 85 and vent 86 are opened. The steam trapped in the cylinder 16 is used for purging the tube of air. The valve 85 and vent 86 are then closed and the steam remaining in the cylinder and tube again condensed, and the steam accumulator and cylinder 16 recharged. The accumulator will hold most of its steam charge after each launching.

In FIG. 9 we have indicated, for example, the fluid pressure conditions in the various parts of the launching apparatus for a missile of the character described launched under the described conditions of a constant acceleration of 3220 ft. per sec. per sec. and an exit velocity of 8000 f.p.s., showing in particular the conditions for maintaining a constant pressure (P of 510 p.s.i. on the base of the combined missile and shoe during travel in the 10,000 ft. launching tube. The normal pressure (P of 5000 p.s.i. in the steam accumulator 34 after a launch is increased to 7500 p.s.i. and 1000 F. in the three day period prior to the next launching. The

hydrogen supply to the cylinder 16 during the same to increase the pressure (P of the hydrogen in the base of the launching tube. The shoe and missile are unlocked one second later and move upwardly at a constant rate of acceleration of 3220 feet per second per second, corresponding to the desired hundred g acceleration rate. The pressure (P rapidly increases to approximately 4000 p.s.i. to maintain a constant pressure (P of 510 p.s.i. on the shoe and missile while in the launching tube. Under these conditions the time required for the missile and shoe to leave the 10,000 foot launching tube will be 2.49 seconds. The missile on leaving the tube with an exit velocity of approximately 8000 f.p.s. will attain an altitude of from -175 miles in less than 4.5 minutes without any additional rocket engine thrust.

Our invention is suitable for the launching of various types of missiles. The internal construction of the missile forms no part of the present invention, and the usual devices for guidance, observation, signalling etc. may be readily incorporated therein.

While in accordance with the provisions of the statutes we have illustrated and described herein a specific form of the invention now known to us, those skilled in the art will understand that changes may be made in the form of the apparatus and method of operation disclosed without departing from the spirit of the invention covered by our claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of other features.

What is claimed is:

1. The method of launching a missile at an exit velocity in excess of 2500 fps. from a long vertical launching tube having a displaceable closure at its upper end which comprises positioning the missile in the lower portion of said vertical tube so as to be movable upwardly on a predetermined pressure being exerted on the underside thereof, providing a substantial vacuum in the portion of said tube above said missile, supplying hydrogen gas at a superatmospheric pressure below said predetermined pressure to a chamber communicating with The hydrogen valves are sequentially opened 6 /2 seconds after the steam valves the space below said missile, compressing said hydrogensure higher than the desired final pressure of said hydrogen gas and in directcontact therewith so as to compress and heat said hydrogen gas, and continuously supplying the compressed high temperature hydrogen gas while at said temperature and in contact with said high density fluid to the space below said missile at a predetermined increasing pressure while said missile is ina free movable condition to cause said missile to movelocityin the range of BOO-10,000 fps. and at a maximum permissible acceleration of not more than 100 gs from a ion vertical launching tubehaving a displaceable. closure'at its upper end which comprises positioning the missile in the lower portion of said vertical tube so as to be movable upwardly on a predetermined pressure being. exerted on the underside thereof, providing a substantial vacuum in the portion of said tube above said missile, supplying. hydrogen. gas at a superatmospheric pressure below saidpredetermined pressure to a chamber communicating with the space below said missile, compressing said hydrogen gas to a value above said predetermin'ed pressure and to a temperature at which its sonic velocity will be above the desired missile exit velocity, by introducing steam at a supercritical pressure higher than the desired final pressure of said hydrogen gas so as to compress and heat said hydrogen gas, and supplying the compressed high temperature hydrogen gas to the space below said missile at a predetermined increasing pressure while said missile is in a freely movable condition to cause said missile to move upwardly in said tube at a substantially constant acceleration not more than 100 gs and exit from theupper end. of said tube.

3. The method of. launching a missile at a high exit velocity from avertical launching tube having a height at least several hundred times its inside diameter which comprises positioning the missile in the lower portion of said vertical tube so as to be movable upwardly on a pre- 7 determined pressure being exerted on the underside thereof, supplying a low density gas at a superatmospheric pressure below said predetermined pressure to a chamber communicating with the space below said missile, introducing a high temperature high density fluid into said chamber at a superatmospheric pressure higher than the desired final pressure of said low density gas and in direct contact therewith so as to rapidly compress said low density gas to a value above said predetermined pressure and to a temperature at which its sonic velocity will be above the desired missile exit velocity, and continuously imposing the compressed low density gas while at said temperature and in contact with said high density fluid on said missile while said missile is in a freely movable condition to cause said missile to move upwardly in said tube at an accelerated speed and a subsequent purging of said tube by said high density fluid.

4. The method of launching a missile at a high exit velocity from a vertical launching tube having a height at least several hundred times its inside diameter which comprises positioning the missile in the lower portion of said vertical tube so as to be movable upwardly on a predetermined pressure being exerted on the underside thereof, supplying a low density gas at a superatmospheric pressure below said predetermined pressure to a chamber communicating with the space below said missile, introducing a high temperature high density fluid into said chamber at a superatmospheric pressure higher than the desired final pressure of said low densit gas and in direct and continuously imposing the compressed low density gas while at said temperature. and in. contact. with said high density fiuid on said missile while said missile isin a freely movable. condition at a substantially constant pressure on the. underside thereof tocause. said missile tomove upwardly. in said tube ata substantially constant rate of acceleration and'a subsequent purging .of said. tube by said high density fluid.

5. The. method. of launching a missile ata high exit. velocity from a vertical launching tube. having. a height at least several hundred times its inside diameter, which comprises positioning the missile in the lower portion of said vertical tube so as to be. movable upwardly on. a predetermined pressure being exerted on the underside thereof, supplying a low density gas at a superatmospheric pressure below said predetermined pressure to a. chamber communicating with the space below said. missile, introducing high temperature. steam into said chamber at a superatmospheric pressure higher than the desired final. pressure of said low density gas and indirect. contact therewith. so as to rapidly compress said. low density gas to. a value above said predetermined pressure and to a temperature at which. its sonic velocity will be above the'desired missile exit velocity, and continuously imposing the compressed low density gas while at said temperature and in contact with said stem on said missile while said missile. is ina freely movable conditionto cause said missile to move. upwardly in said. tube at an accelerated speed and a subsequent purging of said tube by said steam.

6. The method of launching a missile at a high exit velocity and at. a maximum permissible. acceleration of not more than gs from a vertical launching tube having a height at least several hundred times its inside diameter which comprises positioning the missile in the lower portion of said verticaltube so as to be movable upwardly on a predetermined pressure being exerted on the underside thereof; supplying a low density gas at a superatmospheric pressure below said predetermined pressure to a chamber communicating with the space below said missile, introducing high temperature steam into said chamber at a supercritical pressure higher than the desired final pressure of said low density gas and in direct contact therewith so as to rapidly compress said low density gas to a value above said predetermined pressure and to a temperature at which its sonic velocity will be above the desired missile exit velocity, continuously imposing the compressed low density gas while at said temperature and in contact with said super-critical pressure steam on said missile while said missile is moving upwardly in said tube at an accelerated speed, and maintaining the flow of supercritical pressure steam until the missile is discharged and the tube is purged of said low density gas.

7. Missile launching apparatus comprising a vertical launching tube having a height at least several hundred times its inside diameter, means for positioning a missile in the lower portion of said tube in a position to have a gaseous pressure imposed on the underside thereof, means forming a compression chamber communicating with the tube space below said missile, means for supplying a low density gas at a superatmospheric pressure to said compression chamber, means for compressing said low density gas in said compression chamber to a high pressure and a high temperature at which its sonic velocity will be above the desired missile exit velocity including means for supplying a higher density gas at a superatmospheric pressure higher than the desired final pressure of said low density gas to said compression chamber in direct contact with said low density gas so as to compress and heat said low density gas to said high temperature,

and sequentially operated valve means arranged to control the gas discharge from said compression chamber for imposing the compressed low density gas at a substantially constant pressure on the underside of said missile while said missile is in a freely movable condition to cause said missile to move upwardly in said tube at a constant rate of acceleration.

8. Missile launching apparatus comprising a vertical launching tube having a height at least several hundred times its inside diameter, means for positioning a missile in the lower portion of said tube in a position to have a gaseous pressure imposed on the underside thereof, means forming a compression chamber communicating with the tube space below said missile, means for supplying a low density gas at a superatmospheric pressure to said compression chamber, means for compressing said low density gas in said compression chamber to a high pressure and a high temperature at which its sonic velocity will be above the desired missile exit velocity including means for supplying steam at a superatmospheric pressure higher than the desired final pressure of said low density gas to said compression chamber in direct contact with said low density gas so as to compress and heat said gas to said high temperature, and means for imposing the compressed low density gas on the underside of said missile while said missile is in a freely movable condition to cause said missile to move upwardly in said tube at a constant rate of acceleration.

9 Missile launching apparatus comprising a vertical launching tube having a height at least several hundred times its inside diameter, means for positioning a missile in the lower portion of said tube in a position to have a gaseous pressure imposed on the underside thereof, means for providing a substantial vacuum in the portion of said tube above said missile, means forming a compression chamber communicating with the tube space below said missile, means for supplying a low density gas at a superatmospheric pressure to said compression chamber, means for compressing said low density gas in said higher than the desired final pressure of said low density gas to said compression chamber in direct contact with low density gas so as to compress and heat said low density gas to said high temperature, and valve means arranged to control the gas discharge from said compression chamber for imposing the compressed low density gas on the underside of said missile while said missile is in a freely movable condition to cause said missile to move upwardly in said tube.

10. Missile launching apparatus comprising a Vertical launching tube having a height at least several hundred times its inside diameter and a displaceable closure at its upper end, means for positioning a missile in the lower portion of said tube in a position to have a gaseous pressure imposed on the underside thereof, means for providing a substantial vacuum in the portion of said tube above said missile, means forming a compression chamber communicating with the tube space below said missile, means for supplying a low density gas at a superatmospheric pressure to said compression chamber, means for compressing said low density gas in said compression chamber to a high pressure and a high temperature at which its sonic velocity will be above the desired missile exit velocity including means for supplying high temperature steam at a supercritical pressure higher than the desired final pressure of said low density gas to said compression chamber in direct contact with said low density gas so as to compress and heat said gas to said high temperature, and sequentially operated valve means arranged to control the gas discharge from said compression chamber for imposing the compressed low density gas at a substantially constant pressure on the underside of said missile while said missile is in a freely movable condition to cause said missile to move upwardly in said tube at a constant rate of acceleration.

References Cited in the tile of this patent UNITED STATES PATENTS 2,591,299 Rowand et a1 Apr. 1, 1952 2,870,675 Salisbury Ian. 27, 1959 2,872,846 Crozier Feb. 10, 1959 2,882,796 Clark et a1. Apr. 21, 1959 2,935,846 Neale et al. May 10, 1960 

1. THE METHOD OF LAUNCHING A MISSILE AT AN EXIT VELOCITY IN EXCESS OF 2500 F.P.S. FROM A LONG VERTICAL LAUNCHING TUBE HAVING A DISPLACEABLE CLOSURE AT ITS UPPER END WHICH COMPRISES POSITIONING THE MISSILE IN THE LOWER PORTION OF SAID VERTICAL TUBE SO AS TO BE MOVABLE UPWARDLY ON A PREDETERMINED PRESSURE BEING EXERTED ON THE UNDERSIDE THEREOF, PROVIDING A SUBSTANTIAL VACUUM IN THE PORTION OF SAID TUBE ABOVE SAID MISSILE, SUPPLYING HYDROGEN GAS AT A SUPERATMOSPHERIC PRESSURE BELOW SAID PREDETERMINED PRESSURE TO A CHAMBER COMMUNICATING WITH THE SPACE BELOW SAID MISSILE, COMPRESSING SAID HYDROGEN GAS TO A VALUE ABOVE SAID PREDETERMINED PRESSURE AND TO A TEMPERATURE AT WHICH ITS SONIC VELOCITY WILL BE ABOVE THE DESIRED MISSILE EXIT VELOCITY, BY INTRODUCING A HIGHER DENSITY GAS INTO SAID CHAMBER AT A SUPERATMOSPHERIC PRESSURE HIGHER THAN THE DESIRED FINAL PRESSURE OF SAID HYDROGEN GAS AND IN DIRECT CONTACT THEREWITH SO AS TO COMPRESS AND HEAT SAID HYDROGEN GAS, AND CONTINUOUSLY SUPPLYING THE COMPRESSED HIGH TEMPERATURE HYDROGEN GAS WHILE AT SAID TEMPERATURE AND IN CONTACT WITH SAID HIGH DENSITY FLUID TO THE SPACE BELOW SAID MISSILE AT A PREDETERMINED INCREASING PRESSURE WHILE SAID MISSILE IS IN A FREE MOVABLE CONDITION TO CAUSE SAID MISSILE TO MOVE UPWARDLY IN SAID TUBE AT A SUBSTANTIALLY CONSTANT RATE OF ACCELERATION AND EXIT FROM THE UPPER END OF SAID TUBE AND A SUBSEQUENT PURGING OF SAID TUBE BY SAID HIGH DENSITY FLUID. 